Modern cooking appliances in the form of convection ovens, especially convection steamers, which can control the corresponding cooking steps by means of cooking programs stored in the control unit, contain cooking steps with cooking times based on the load on an individual tray or rack. The quantities of food to be cooked which are loaded into cooking appliances, however, can differ considerably. Thus, when only half of the trays or racks are occupied by the food to be cooked, the cooking appliance is said to have only half a load, whereas, when all of the trays or racks are full, the cooking appliance is said to be fully loaded.
The heating power delivered by the cooking appliance must be allocated depending on the number of loaded trays. This allocation is relevant during the heating-up phase at the beginning of the cooking process. The material to be cooked, which is initially cold, lowers the temperature in the cooking chamber or cooking compartment, which may have been preheated to a nominal temperature. By means of the temperature controller, the heating device of the cooking chamber is used to bring the temperature back up to the nominal value. Because of the finite heating power of the heating device, this process is dependent on the size of the load. This means that, when the load is large, it takes longer to reach the nominal temperature than when the load is small. During the heating-up phase, it can be seen that, depending on the heating energy input, which is allocated in correspondence with the load, the larger the load, the longer the heating phase.
To compensate for the differences between loads, a core temperature sensor is often used, which has one or more probes to measure the temperature in the food itself. The cooking process is then not terminated after a fixed time but rather as a function of the core temperature which has been reached. Core temperature sensors, however, suffer from the disadvantages that, first, they must be present in the first place; second, they must be correctly inserted; and, third, in the case of many products such as frozen food, small items such as peas, etc., they can be used only with difficulty or not at all.
An object of the present invention is therefore to provide a method for operating a cooking appliance in the form of a convection oven, a hot-air steamer, or a convection steamer, by means of which the cooking time is adjusted automatically as a function of the load in the cooking chamber without the need for a core temperature sensor. This object is achieved by the features in claim 1.